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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CREATE OPERATOR CLASS</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-createoperator.html" title="CREATE OPERATOR" /><link rel="next" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE OPERATOR CLASS</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createoperator.html" title="CREATE OPERATOR">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATEOPCLASS"><div class="titlepage"></div><a id="id-1.9.3.73.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE OPERATOR CLASS</span></h2><p>CREATE OPERATOR CLASS — define a new operator class</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE OPERATOR CLASS <em class="replaceable"><code>name</code></em> [ DEFAULT ] FOR TYPE <em class="replaceable"><code>data_type</code></em>
USING <em class="replaceable"><code>index_method</code></em> [ FAMILY <em class="replaceable"><code>family_name</code></em> ] AS
{ OPERATOR <em class="replaceable"><code>strategy_number</code></em> <em class="replaceable"><code>operator_name</code></em> [ ( <em class="replaceable"><code>op_type</code></em>, <em class="replaceable"><code>op_type</code></em> ) ] [ FOR SEARCH | FOR ORDER BY <em class="replaceable"><code>sort_family_name</code></em> ]
| FUNCTION <em class="replaceable"><code>support_number</code></em> [ ( <em class="replaceable"><code>op_type</code></em> [ , <em class="replaceable"><code>op_type</code></em> ] ) ] <em class="replaceable"><code>function_name</code></em> ( <em class="replaceable"><code>argument_type</code></em> [, ...] )
| STORAGE <em class="replaceable"><code>storage_type</code></em>
} [, ... ]
</pre></div><div class="refsect1" id="id-1.9.3.73.5"><h2>Description</h2><p>
<code class="command">CREATE OPERATOR CLASS</code> creates a new operator class.
An operator class defines how a particular data type can be used with
an index. The operator class specifies that certain operators will fill
particular roles or <span class="quote">“<span class="quote">strategies</span>”</span> for this data type and this
index method. The operator class also specifies the support functions to
be used by
the index method when the operator class is selected for an
index column. All the operators and functions used by an operator
class must be defined before the operator class can be created.
</p><p>
If a schema name is given then the operator class is created in the
specified schema. Otherwise it is created in the current schema.
Two operator classes in the same schema can have the same name only if they
are for different index methods.
</p><p>
The user who defines an operator class becomes its owner. Presently,
the creating user must be a superuser. (This restriction is made because
an erroneous operator class definition could confuse or even crash the
server.)
</p><p>
<code class="command">CREATE OPERATOR CLASS</code> does not presently check
whether the operator class definition includes all the operators and
functions required by the index method, nor whether the operators and
functions form a self-consistent set. It is the user's
responsibility to define a valid operator class.
</p><p>
Related operator classes can be grouped into <em class="firstterm">operator
families</em>. To add a new operator class to an existing family,
specify the <code class="literal">FAMILY</code> option in <code class="command">CREATE OPERATOR
CLASS</code>. Without this option, the new class is placed into
a family named the same as the new class (creating that family if
it doesn't already exist).
</p><p>
Refer to <a class="xref" href="xindex.html" title="38.16. Interfacing Extensions to Indexes">Section 38.16</a> for further information.
</p></div><div class="refsect1" id="id-1.9.3.73.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
The name of the operator class to be created. The name can be
schema-qualified.
</p></dd><dt><span class="term"><code class="literal">DEFAULT</code></span></dt><dd><p>
If present, the operator class will become the default
operator class for its data type. At most one operator class
can be the default for a specific data type and index method.
</p></dd><dt><span class="term"><em class="replaceable"><code>data_type</code></em></span></dt><dd><p>
The column data type that this operator class is for.
</p></dd><dt><span class="term"><em class="replaceable"><code>index_method</code></em></span></dt><dd><p>
The name of the index method this operator class is for.
</p></dd><dt><span class="term"><em class="replaceable"><code>family_name</code></em></span></dt><dd><p>
The name of the existing operator family to add this operator class to.
If not specified, a family named the same as the operator class is
used (creating it, if it doesn't already exist).
</p></dd><dt><span class="term"><em class="replaceable"><code>strategy_number</code></em></span></dt><dd><p>
The index method's strategy number for an operator
associated with the operator class.
</p></dd><dt><span class="term"><em class="replaceable"><code>operator_name</code></em></span></dt><dd><p>
The name (optionally schema-qualified) of an operator associated
with the operator class.
</p></dd><dt><span class="term"><em class="replaceable"><code>op_type</code></em></span></dt><dd><p>
In an <code class="literal">OPERATOR</code> clause,
the operand data type(s) of the operator, or <code class="literal">NONE</code> to
signify a prefix operator. The operand data
types can be omitted in the normal case where they are the same
as the operator class's data type.
</p><p>
In a <code class="literal">FUNCTION</code> clause, the operand data type(s) the
function is intended to support, if different from
the input data type(s) of the function (for B-tree comparison functions
and hash functions)
or the class's data type (for B-tree sort support functions,
B-tree equal image functions, and all functions in GiST,
SP-GiST, GIN and BRIN operator classes). These defaults are
correct, and so <em class="replaceable"><code>op_type</code></em> need not be specified
in <code class="literal">FUNCTION</code> clauses, except for the case of a
B-tree sort support function that is meant to support
cross-data-type comparisons.
</p></dd><dt><span class="term"><em class="replaceable"><code>sort_family_name</code></em></span></dt><dd><p>
The name (optionally schema-qualified) of an existing <code class="literal">btree</code> operator
family that describes the sort ordering associated with an ordering
operator.
</p><p>
If neither <code class="literal">FOR SEARCH</code> nor <code class="literal">FOR ORDER BY</code> is
specified, <code class="literal">FOR SEARCH</code> is the default.
</p></dd><dt><span class="term"><em class="replaceable"><code>support_number</code></em></span></dt><dd><p>
The index method's support function number for a
function associated with the operator class.
</p></dd><dt><span class="term"><em class="replaceable"><code>function_name</code></em></span></dt><dd><p>
The name (optionally schema-qualified) of a function that is an
index method support function for the operator class.
</p></dd><dt><span class="term"><em class="replaceable"><code>argument_type</code></em></span></dt><dd><p>
The parameter data type(s) of the function.
</p></dd><dt><span class="term"><em class="replaceable"><code>storage_type</code></em></span></dt><dd><p>
The data type actually stored in the index. Normally this is
the same as the column data type, but some index methods
(currently GiST, GIN, SP-GiST and BRIN) allow it to be different. The
<code class="literal">STORAGE</code> clause must be omitted unless the index
method allows a different type to be used.
If the column <em class="replaceable"><code>data_type</code></em> is specified
as <code class="type">anyarray</code>, the <em class="replaceable"><code>storage_type</code></em>
can be declared as <code class="type">anyelement</code> to indicate that the index
entries are members of the element type belonging to the actual array
type that each particular index is created for.
</p></dd></dl></div><p>
The <code class="literal">OPERATOR</code>, <code class="literal">FUNCTION</code>, and <code class="literal">STORAGE</code>
clauses can appear in any order.
</p></div><div class="refsect1" id="id-1.9.3.73.7"><h2>Notes</h2><p>
Because the index machinery does not check access permissions on functions
before using them, including a function or operator in an operator class
is tantamount to granting public execute permission on it. This is usually
not an issue for the sorts of functions that are useful in an operator
class.
</p><p>
The operators should not be defined by SQL functions. An SQL function
is likely to be inlined into the calling query, which will prevent
the optimizer from recognizing that the query matches an index.
</p><p>
Before <span class="productname">PostgreSQL</span> 8.4, the <code class="literal">OPERATOR</code>
clause could include a <code class="literal">RECHECK</code> option. This is no longer
supported because whether an index operator is <span class="quote">“<span class="quote">lossy</span>”</span> is now
determined on-the-fly at run time. This allows efficient handling of
cases where an operator might or might not be lossy.
</p></div><div class="refsect1" id="id-1.9.3.73.8"><h2>Examples</h2><p>
The following example command defines a GiST index operator class
for the data type <code class="literal">_int4</code> (array of <code class="type">int4</code>). See the
<a class="xref" href="intarray.html" title="F.20. intarray">intarray</a> module for the complete example.
</p><pre class="programlisting">
CREATE OPERATOR CLASS gist__int_ops
DEFAULT FOR TYPE _int4 USING gist AS
OPERATOR 3 &&,
OPERATOR 6 = (anyarray, anyarray),
OPERATOR 7 @>,
OPERATOR 8 <@,
OPERATOR 20 @@ (_int4, query_int),
FUNCTION 1 g_int_consistent (internal, _int4, smallint, oid, internal),
FUNCTION 2 g_int_union (internal, internal),
FUNCTION 3 g_int_compress (internal),
FUNCTION 4 g_int_decompress (internal),
FUNCTION 5 g_int_penalty (internal, internal, internal),
FUNCTION 6 g_int_picksplit (internal, internal),
FUNCTION 7 g_int_same (_int4, _int4, internal);
</pre></div><div class="refsect1" id="id-1.9.3.73.9"><h2>Compatibility</h2><p>
<code class="command">CREATE OPERATOR CLASS</code> is a
<span class="productname">PostgreSQL</span> extension. There is no
<code class="command">CREATE OPERATOR CLASS</code> statement in the SQL
standard.
</p></div><div class="refsect1" id="id-1.9.3.73.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alteropclass.html" title="ALTER OPERATOR CLASS"><span class="refentrytitle">ALTER OPERATOR CLASS</span></a>, <a class="xref" href="sql-dropopclass.html" title="DROP OPERATOR CLASS"><span class="refentrytitle">DROP OPERATOR CLASS</span></a>, <a class="xref" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY"><span class="refentrytitle">CREATE OPERATOR FAMILY</span></a>, <a class="xref" href="sql-alteropfamily.html" title="ALTER OPERATOR FAMILY"><span class="refentrytitle">ALTER OPERATOR FAMILY</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-createoperator.html" title="CREATE OPERATOR">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE OPERATOR </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="40%" align="right" valign="top"> CREATE OPERATOR FAMILY</td></tr></table></div></body></html>
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